The present invention relates to fiber optic cable splices and, more particularly, to an arrangement for providing metallic sheath bonding at cable splice locations.
Fiber optic cable has become a standard transmission medium for many different communication systems. In general, a fiber optic cable consists of a number of a separate optical fibers stranded together, and (usually) including a central metallic strength member to provide outer mechanical support to the cable, as well as to provide an electric signal path that is used to send certain operational tones along the length of the cable. Plastic coatings (in general, a poly-based material) may then be used to cover the metallic sheath, particularly when the cable is to be buried in the ground.
Electrical bonding of the metallic sheath layer of one fiber optic cable to another at a splice location is essential for protection from lightning or stray voltages induced from power lines, as well as for proper operation of cable-locating tones. The current practice of bonding cable sheaths requires that the cable be stripped of its outer poly coating and a grounding lug be inserted underneath a grip block in the splice closure, with each cable grounded to the splice closure housing. Most splice closure housings are constructed of metallic material so that the electrical continuity of the cables is retained through this connection to the closure housing. However, this method is considered to be poor at best, since temperature changes may cause this arrangement to become released, allowing for lightning strikes and/or stray voltages to burn at locations where there is a poor connection. This will result in damage to the delicate fibers housed inside the metallic/poly cable housing.
Thus, a need remains in the art for a better method of providing for bonding of the metallic sheaths of fiber cables at splice locations.
The need remaining in the art is addressed by the present invention, which relates to fiber optic cable splices and, more particularly, to an arrangement for providing metallic sheath bonding at fiber optic cable splice locations. In accordance with the present invention, a specially-formed metallic bond lug is disposed to surround the outer poly coating layer of each fiber optic cable. The bond lug is formed to include a plurality of barbed metallic teeth on its underside that will penetrate the exterior poly sheath and contact the underlying metallic sheath layer, allowing the sheath layer to be bonded via the connection to the barbed teeth. The bond lugs on a pair of fiber optic cables can be electrically connected through a wire cable to provide continuity between the sheath layers on the pair of fiber optic cables. Thus, the use of a barbed bond lug in accordance with the present invention eliminates the time and expense associated with stripping away the outer poly covering layer, as was required in prior art arrangements.
In a preferred embodiment of the present invention, the metallic bond lug is formed as a xe2x80x9cclam shellxe2x80x9d element that can easily be clamped to surround cables of different diameters, and properly torqued down with a screwdriver or adjustable wrench. Inserts may be disposed within the lug to prevent over-tightening, which would cause the barbed teeth to penetrate the sheath layer and extend into the fibers themselves.
A threaded bolt may be included and extend from the bond lug for attachment of a bonding ribbon (the opposite end of the ribbon then being attached to the bond lug of the other cable in the splice), or used to provide a xe2x80x9cgroundxe2x80x9d attachment for the arrangement.